Increasing Contributions of Peatlands to Boreal Evapotranspiration in a Warming Climate

Manuel Helbig
James Michael Waddington
Pavel Alekseychik
Brian Amiro
Mika Aurela
Alan Barr
Andrew Black
Peter Blanken
Sean Carey
Jiquan Chen
Jinshu Chi
Ankur Desai
Allison Dunn
Eugenie Euskirchen
Lawrence Flanagan
Inke Forbrich
Thomas Friborg
Achim Grelle
Silvie Harder
Michal Heliasz
Elyn Humphreys
Hiroki Lkawa
Pierre-Erik Isabelle
Hiroki Iwata
Rachhpal Jassal
Mika Korkiakoski
Juliya Kurbatova
Lars Kutzbach
Anders Lindroth
Mikaell Ottosson Lofvenius
Annalea Lohila
Ivan Mammarella
Philip Marsh
Trofim Maximov
Joe Melton
Paul Moore
Daniel Nadeau
Erin Nicholls
Mats Nilsson
Takeshi Ohta
Matthias Peichl
Richard Petrone
Roman Petrov
Anatoly Prokushkin
William Quinton
David Reed
Nigel Roulet
Benjamin Runkle
Oliver Sonnentag
Ian Stachan
Pierre Taillardat
Eeva-Stiina Tuittila
Juha-Pekka Tuovinen
Jessica Turner
Masahito Ueyama
Andrej Varlagin
Martin Wilmking
Steven Wofsy
Vyacheslav Zyianov
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The response of evapotranspiration (ET) to warming is of critical importance to the water and carbon cycle of the boreal biome, a mosaic of land cover types dominated by forests and peatlands. The effect of warming-induced vapour pressure deficit (VPD) increases on boreal ET remains poorly understood because peatlands are not specifically represented as plant functional types in Earth system models. Here we show that peatland ET increases more than forest ET with increasing VPD using observations from 95 eddy covariance tower sites. At high VPD of more than 2 kPa, peatland ET exceeds forest ET by up to 30%. Future (2091–2100) mid-growing season peatland ET is estimated to exceed forest ET by over 20% in about one-third of the boreal biome for RCP4.5 and about two-thirds for RCP8.5. Peatland-specific ET responses to VPD should therefore be included in Earth system models to avoid biases in water and carbon cycle projections